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@@ -12,6 +12,8 @@
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GRUB 2 reads its configuration from the `/boot/grub2/grub.cfg` file on traditional BIOS-based machines and from the `/boot/efi/EFI/fedora/grub.cfg` file on UEFI machines. This file contains menu information.
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+ Note that the postinstall script of `grub2-common` installs a small shim which chains the UEFI-based config at `/boot/efi/EFI/fedora/grub.cfg` to the standard configuration at `/boot/grub2/grub.cfg`. To reset this shim to defaults, delete the existing `/boot/efi/EFI/fedora/grub.cfg` and then `dnf reinstall grub2-common`.
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+
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The GRUB 2 configuration file, `grub.cfg`, is generated during installation, or by invoking the [application]*/usr/sbin/grub2-mkconfig* utility, and is automatically updated by [command]#grubby# each time a new kernel is installed. When regenerated manually using [application]*grub2-mkconfig*, the file is generated according to the template files located in `/etc/grub.d/`, and custom settings in the `/etc/default/grub` file. Edits of `grub.cfg` will be lost any time [application]*grub2-mkconfig* is used to regenerate the file, so care must be taken to reflect any manual changes in `/etc/default/grub` as well.
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Normal operations on `grub.cfg`, such as the removal and addition of new kernels, should be done using the [command]#grubby# tool and, for scripts, using [command]#new-kernel-pkg# tool. If you use [command]#grubby# to modify the default kernel the changes will be inherited when new kernels are installed. For more information on [command]#grubby#, see xref:#sec-Making_Persistent_Changes_to_a_GRUB_2_Menu_Using_the_grubby_Tool[Making Persistent Changes to a GRUB 2 Menu Using the grubby Tool].
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@@ -277,18 +279,19 @@
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Changes to `/etc/default/grub` require rebuilding the `grub.cfg` file as follows:
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- * On BIOS-based machines, issue the following command as `root`:
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+ * Issue the following command as `root`:
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[subs="attributes"]
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----
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~]#{nbsp}grub2-mkconfig -o /boot/grub2/grub.cfg
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----
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- * On UEFI-based machines, issue the following command as `root`:
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+ * On UEFI-based machines the a chaining shim to `/boot/grub2/grub.cfg` should be installed in `/boot/efi/EFI/fedora/grub.cfg`. This shim can be recreated/reset as follows:
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[subs="attributes"]
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----
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- ~]#{nbsp}grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}rm /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}dnf reinstall grub2-common
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----
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[[sec-Editing_a_Menu_Entry]]
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@@ -304,18 +307,19 @@
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Changes to `/etc/default/grub` require rebuilding the `grub.cfg` file as follows:
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- * On BIOS-based machines, issue the following command as `root`:
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+ * Issue the following command as `root`:
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[subs="attributes"]
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----
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~]#{nbsp}grub2-mkconfig -o /boot/grub2/grub.cfg
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----
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- * On UEFI-based machines, issue the following command as `root`:
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+ * On UEFI-based machines the a chaining shim to `/boot/grub2/grub.cfg` should be installed in `/boot/efi/EFI/fedora/grub.cfg`. This shim can be recreated/reset as follows:
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[subs="attributes"]
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----
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- ~]#{nbsp}grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}rm /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}dnf reinstall grub2-common
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----
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[[sec-Adding_a_new_Entry]]
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@@ -361,9 +365,9 @@
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====
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- . On BIOS-based machines, copy the contents of `/boot/grub2/grub.cfg`, or, on UEFI machines, copy the contents of `/boot/efi/EFI/fedora/grub.cfg`. Put the content of the `grub.cfg` into the `/etc/grub.d/40_custom` file below the existing header lines. The executable part of the `40_custom` script has to be preserved.
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+ . Copy the contents of `/boot/grub2/grub.cfg`. Put the content of the `grub.cfg` into the `/etc/grub.d/40_custom` file below the existing header lines. The executable part of the `40_custom` script has to be preserved.
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- . From the content put into the `/etc/grub.d/40_custom` file, only the `menuentry` blocks are needed to create the custom menu. The `/boot/grub2/grub.cfg` and `/boot/efi/EFI/fedora/grub.cfg` files might contain function specifications and other content above and below the `menuentry` blocks. If you put these unnecessary lines into the `40_custom` file in the previous step, erase them.
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+ . From the content put into the `/etc/grub.d/40_custom` file, only the `menuentry` blocks are needed to create the custom menu. The `/boot/grub2/grub.cfg` file might contain function specifications and other content above and below the `menuentry` blocks. If you put these unnecessary lines into the `40_custom` file in the previous step, erase them.
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This is an example of a custom `40_custom` script:
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@@ -414,25 +418,26 @@
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** `01_users` (if it exists),
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** and `README`.
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-
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+ +
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Alternatively, if you want to keep the files in the `/etc/grub2.d/` directory, make them unexecutable by running the [command]#chmod a-x <file_name># command.
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. Edit, add, or remove menu entries in the `40_custom` file as desired.
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. Rebuild the `grub.cfg` file by running the [command]#grub2-mkconfig -o# command as follows:
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-
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- ** On BIOS-based machines, issue the following command as `root`:
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-
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+ +
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+ ** Issue the following command as `root`:
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+ +
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[subs="attributes"]
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----
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~]#{nbsp}grub2-mkconfig -o /boot/grub2/grub.cfg
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----
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- ** On UEFI-based machines, issue the following command as `root`:
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-
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+ ** On UEFI-based machines the a chaining shim to `/boot/grub2/grub.cfg` should be installed in `/boot/efi/EFI/fedora/grub.cfg`. This shim can be recreated/reset as follows:
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+ +
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[subs="attributes"]
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----
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- ~]#{nbsp}grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}rm /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}dnf reinstall grub2-common
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----
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[[sec-GRUB_2_Password_Protection]]
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@@ -453,7 +458,7 @@
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=== Setting Up Users and Password Protection, Specifying Menu Entries
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. To specify a superuser, add the following lines in the `/etc/grub.d/01_users` file, where `john` is the name of the user designated as the superuser, and `johnspassword` is the superuser's password:
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-
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+ +
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[subs="quotes"]
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----
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cat <<EOF
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@@ -463,7 +468,7 @@
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----
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. To allow other users to access the menu entries, add additional lines per user at the end of the `/etc/grub.d/01_users` file.
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-
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+ +
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[subs="quotes"]
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----
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cat <<EOF
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@@ -474,7 +479,7 @@
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----
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. When the users and passwords are set up, specify the menu entries that should be password-protected in the `/etc/grub.d/40_custom` file in a similar fashion to the following:
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-
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+ +
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[subs="quotes, attributes"]
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----
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@@ -508,18 +513,19 @@
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Rebuild the `grub.cfg` file by running the [command]#grub2-mkconfig -o# command as follows:
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- * On BIOS-based machines, issue the following command as `root`:
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+ * Issue the following command as `root`:
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[subs="attributes"]
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----
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~]#{nbsp}grub2-mkconfig -o /boot/grub2/grub.cfg
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----
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- * On UEFI-based machines, issue the following command as `root`:
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+ * On UEFI-based machines the a chaining shim to `/boot/grub2/grub.cfg` should be installed in `/boot/efi/EFI/fedora/grub.cfg`. This shim can be recreated/reset as follows:
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[subs="attributes"]
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----
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- ~]#{nbsp}grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}rm /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}dnf reinstall grub2-common
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----
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[[sec-Password_Encryption]]
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@@ -594,26 +600,27 @@
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. Run the [command]#rm /etc/sysconfig/grub# command;
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. For EFI systems *only*, run the following command:
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-
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+ +
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[subs="attributes"]
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----
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~]#{nbsp}dnf reinstall grub2-efi shim grub2-tools
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----
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. Rebuild the `grub.cfg` file by running the [command]#grub2-mkconfig -o# command as follows:
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-
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- ** On BIOS-based machines, issue the following command as `root`:
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-
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+ +
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+ ** Issue the following command as `root`:
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+ +
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[subs="attributes"]
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----
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~]#{nbsp}grub2-mkconfig -o /boot/grub2/grub.cfg
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----
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-
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- ** On UEFI-based machines, issue the following command as `root`:
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-
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+ +
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+ ** On UEFI-based machines the a chaining shim to `/boot/grub2/grub.cfg` should be installed in `/boot/efi/EFI/fedora/grub.cfg`. This shim can be recreated/reset as follows:
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+ +
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[subs="attributes"]
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----
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- ~]#{nbsp}grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}rm /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}dnf reinstall grub2-common
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----
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. Now follow the procedure in xref:#sec-Reinstalling_GRUB_2[Reinstalling GRUB 2] to restore GRUB2 on the `/boot/` partition.
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@@ -656,18 +663,19 @@
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Rebuild the `grub.cfg` file by running the [command]#grub2-mkconfig -o# command as follows:
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- * On BIOS-based machines, issue the following command as `root`:
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+ * Issue the following command as `root`:
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[subs="attributes"]
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----
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~]#{nbsp}grub2-mkconfig -o /boot/grub2/grub.cfg
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----
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- * On UEFI-based machines, issue the following command as `root`:
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+ * On UEFI-based machines the a chaining shim to `/boot/grub2/grub.cfg` should be installed in `/boot/efi/EFI/fedora/grub.cfg`. This shim can be recreated/reset as follows:
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[subs="attributes"]
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----
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- ~]#{nbsp}grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}rm /boot/efi/EFI/fedora/grub.cfg
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+ ~]#{nbsp}dnf reinstall grub2-common
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----
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[NOTE]
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rocketraman
commented 2 years ago
The system administrators guide recommends overwriting the EFI grub.cfg shim installed by grub2-common. This will also leave essentially duplicate information in
/boot/grub2/grub.cfgand/boot/efi/EFI/fedora/grub.cfgwith the former being ignored by the system.Correct these docs so that the shim is not overwritten (and explain how to restore it if previously broken via out-of-date docs), and grub2 configuration on end-user systems is always consistently in one place:
/boot/grub2/grub.cfg.Also fixed some issues with list numbering not being continuous.